Sorry for the beginner question but I can't seem to figure out how to
add or remove values from an array of variable size. For example,
this works without problem:
Public Class Form1
Public config(2) As String
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
config(0) = "test"
end sub
End Class
This however doesn't... I've tried various variations on this and I can't seem to figure it out.
Public Class Form1
Public config() As String
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
config(0) = "test"
end sub
End Class
How do I add or remove elements from an array in this very basic situation
Adding and Removing from a variable Array?
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Adding and Removing from a variable Array?
drewex
kaborka
Redim config(2)
config(0) = "test"
OzerK
OK, the first works as youve dimensioned an provided the array with a dimension which will instantiate the array object.
The second will fail as youve established a reference variable to an array but havent given it any dimensions so it isnt yet instantiated.
Using the second will give you and "Object reference not set to an instance of an object." exception just like if you do a
dim x as Class1 and then try and use x. You need to do a dim x as New Class1 to instantiate a new instance of Class1 as an Object.
WHy would you want the second. You may have an array you want as class level scoped but want to dimension it in a method. So you need to specify the array as a class level variable and provide the dimension in the method.
The following code example will work if you press button1 before button2 as button1 as button1 adds dimension to the array and hence instantiates it. If you then press button2 it will display the contents.
If you restart the program and press button2 first it will fail because the array has not yet been dimensioned, press button1 and button2 again and it will display the contents.
Public Class Form1
Public s() As String
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
ReDim s(2)
s(0) = "dddd"
MsgBox(s(0))
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
MsgBox(s(0))
End Sub
End Class
Redim allows you to redimension an array after its been created with a few limitations
http://msdn.microsoft.com/library/default.asp url=/library/en-us/script56/html/5c12ce79-6616-4144-b3b6-4cffe3884dfd.asp
joelw7
In addition to what Spotty said, if you want dynamically sized arrays, look into the StringCollection, ArrayList, and other objects in the System.Collections.Specialized namespace. Also, in 2005, consider the new generic lists.
Jim Wooley
http://devauthority.com/blogs/jwooley/default.aspx